I know it is him, not me and I always tell myself not to let him upset me, but I do.
Hello Ms. Sunshine and welcome to the family. I'm so sorry you're going through this and it sounds like a nightmare situation. I was also in a similar position a few years ago and long story short, I sold the house and walked away. Not what I wanted, but breaking up is about what's best for the future. I had to let go and move on so I could actually heal.
I also wanted to quickly comment on the part above since it's not exactly true. You might not feel any fault for what happens with him, but each of us played a part by invalidating our partner's feelings and pouring gasoline on the fire, so to speak.
Now, it's not our fault for having little understanding of mental illness, and you can change the patterns by making some healthy boundaries and learning to lead with empathy when your ex partner is disordered.
From his point of view, you've ruined him and it's all your fault, which is something that cycles through his brain throughout the day. Why? Well, he's mentally ill and great at self-sabotaging his life. So he feels like his actions are justified because you're so insensitive and horrible to him.
Now, you'll say none of that is true....and to you it's not. But again, he's mentally ill and thinking through a disordered lens. It's 100% true for him and why all the chaos has ensued.
To change this dynamic, you must understand that he's sick and show compassion for what he's going through. And again, I know if feels like you're the victim here...but you're actually both victims to his mental illness. Everything about this sucks but you can't walk away and you can't force him to move/sell without a court order, which is a long, expensive process.
So the easiest way forward here is to change the communication dynamics, which comes from you initially since he's incapable of leading.
When he's disordered, ignore every single word that comes out of his mouth and focus on his emotions instead. If he's angry, calm him down. If he's sad, cheer him up. Just be there for him like you would a small child in the exact same circumstances. Once he realizes that you genuinely care and you're looking out for him, the over the top stuff minimizes and you can get back to some semblance of a normal life again.
If it were me (and it was a few months ago), I'd walk away and tell him good luck with the mortgage on his own. I'd find someone to temporarily take in the farm animals and I'd be in a new house/apartment by next week. Maybe that ruins your credit for seven years but that's a small price to pay for your sanity.
Those are your options though: walk away or learn to communicate more effectively with him. Both options stink and neither are fair, but that's the cards you've been dealt here. I hope that helps!